Process for producing volatile organic compounds from biomass material

ABSTRACT

Embodiments of the present invention provide for efficient and economical production and recovery of ethanol or other volatile organic compounds, such as acetic acid, from solid biomass material, particularly on a larger scale, such as on the commercialization or industrial scale. According to one aspect of the invention, the method comprises (a) generating at least about 10 tons of prepared biomass material by adding a microbe, optionally an acid, and optionally, an enzyme to a solid biomass; (b) storing the prepared biomass material for at least about 24 hours in a storage facility to allow production of at least one volatile organic compound from at least a portion of the sugar in the solid biomass; and (c) capturing the at least one volatile organic compound by using a solventless recovery system.

REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationNo. 61/648,109, filed on May 17, 2012, U.S. Provisional Application No.61/786,844, filed on Mar. 15, 2013, and U.S. Provisional Application No.61/786,860, filed on Mar. 15, 2013, the disclosures of which areincorporated by reference herein in their entirety.

FIELD OF THE INVENTION

Embodiments of this invention relate generally to a process forproducing volatile organic compounds, such as ethanol, from biomassmaterial, and more particularly to fermentation and recovery of suchvolatile organic compounds from biomass material.

BACKGROUND OF THE INVENTION

This section is intended to introduce various aspects of the art, whichmay be associated with exemplary embodiments of the present invention.This discussion is believed to assist in providing a framework tofacilitate a better understanding of particular aspects of the presentinvention. Accordingly, it should be understood that this section shouldbe read in this light, and not necessarily as admissions of any priorart.

As the world's petroleum supplies continue to diminish there is agrowing need for alternative materials that can be substituted forvarious petroleum products, particularly transportation fuels. In theU.S., environmental regulations, such as the Clean Air Act of 1990,provide incentives for the use of oxygenated fuels in automobiles.Ethanol or methyl tertiary butyl ether (MTBE) boosts the oxygen contentin gasoline and reduces carbon monoxide emissions. One principaladvantage for the use of ethanol is that the fuel is produced fromrenewable resources. Atmospheric levels of carbon dioxide, a greenhousegas, can be decreased by replacing fossil fuels with renewable fuels.

Currently much effort is underway to produce bioethanol that is derivedfrom renewable biomass materials, such as corn, sugar crops, energycrops, and solid waste. Conventional ethanol production from corntypically competes with valuable food resources, which can be furtheramplified by increasingly more severe climate conditions, such asdroughts and floods, which negatively impact the amount of cropharvested every year. The competition from conventional ethanolproduction can drive up food prices. While other crops have served asthe biomass material for ethanol production, they usually are notsuitable for global implementations due to the climate requirements ofsuch crops. For instance, ethanol can also be efficiently produced fromsugar cane, but only in certain areas of the world, such as Brazil, thathave a climate that can support near-year-round harvest.

While other approaches of producing ethanol that do not use corn areavailable, they are still lacking. For example, Henk and Linden atColorado State University investigated solid-state production of ethanolfrom sorghum (see Solid State Production of Ethanol from Sorghum, LindaL. Henk and James C. Linden, Applied Biochemistry and Biotechnology,Vol. 57/58, 1996, pp. 489-501). They noted for sweet sorghum to be usedsuccessfully for ethanol production, three issues needed to beaddressed:

-   -   Carbohydrate storage;    -   Accessibility of the ligno-cellulosic fraction to enzymatic        hydrolysis of hemicellulose and cellulose; and    -   A more economical means of recovering the ethanol from the sweet        sorghum.

In their process, they pointed out that seasonal availability andstorability of sweet sorghum are important factors in the use of thisrenewable biomass. Sugar extraction and storability are two seriousproblems that have limited the use of sweet sorghum as a substrate forethanol production. Traditional applications envision using juicecontaining about 10-15% sugar that has been extracted or pressed fromthe sweet sorghum pulp. The juice is then either fermented directly toalcohol or evaporated to molasses for storage. Direct fermentation ofthe juice to ethanol is a seasonal process, accomplished for only ashort time after harvest. This presents challenges to scaling up solidstate fermentation from an experimental stage to a larger practicalstage, such as industrial scale. For example, the short harvestingwindow requires a substantial capital investment of storage space andrecovery facilities to process the peak amount for a short period timewhile the space and equipment would sit dormant or be under-utilized forthe down time.

Henk and Linden's strategy to some of the problems of making sweetsorghum to ethanol was to investigate using wet stored solid statefermentation integrated into an economical method for long-term storageof ethanol in sweet sorghum. While Henk and Linden did show someimprovements in the overall process, there are still a number ofshortcomings, including the amount of ethanol they were able to produce.Such proposed systems tend to make bioethanol production even moreexpensive by typically requiring expensive equipment that needs costlymaintenance. Also, Henk and Linden showed feasibility of solid statefermentation of sorghum on an experimental scale but did not providedetails for a scale up operation.

For instance, Henk and Linden did not provide any means to economicallyrecover the ethanol and other volatile organic compounds from thebiomass solid material. Henk and Linden and others have not addressedthe obstacles that render ethanol production from solid-statefermentation of sorghum economically feasible when it is operated on alarger scale, particularly an industrial scale.

Others have also recognized challenges to economically recover theethanol and other volatile organic compounds from the biomass solidmaterial. For instance, Webster et al. reported that using a forageharvester for sweet sorghum results in rapid juice deterioration andtherefore not an attractive solution for bringing in sweet sorghum tosugar mills (see Observations of the Harvesting, Transporting and TrialCrushing of Sweet Sorghum in a Sugar Mill, Webster, A., et al, 2004Conference of the Australian Society of Sugar Cane Technologist,Brisbane, Queensland, Australia (May 2004)). Andrzejewski and Egglestonreported that challenges in making U.S. sweet sorghum to ethanol (orother uses) viable revolve around the storage of the juice because ofthe relatively narrow harvest window of sweet sorghum in the UnitedStates (see Development of commercially viable processing technologiesfor sweet sorghum at USDA-ARS-Southern Regional Research Center in NewOrleans, Andrzejewski and Eggleston, Sweet Sorghum Ethanol Conference,Jan. 26, 2012). In particular, the challenges include (i) clarification(removal of suspended and turbid particles) of the raw juice to make itsuitable for concentration and/or fermentation, (ii) stabilization ofjuice or partially concentrated juice for cost-effective seasonal use(liquid feedstock), and (iii) concentration of juice into syrup forstorage, year-round supply, and efficient transport (liquid feedstock).

Bellmer sought to improve the process by optimizing conditions aroundremoving the juice from the solids before processing (see The untappedpotential of Sweet Sorghum as a Bioenergy Feedstock, Bellmer, D., SweetSorghum Ethanol Conference, Jan. 26, 2012). Wu et al. recognized thetechnical challenges of using sweet sorghum for biofuels, including ashort harvest period for highest sugar content, and fast sugardegradation during storage (see Features of sweet sorghum juice andtheir performance in ethanol fermentation, X. Wu et al., IndustrialCrops and Products 31: 164-170, 2010). In particular, the study showedthat as much as 20% of the fermentable sugars can be lost in 3 days.Bennet and Annex noted the limitations of using sorghum for ethanolproduction involving material transport cost and storability (seeFarm-gate productions costs of sweet sorghum as a bioethanol feedstock,Transactions of the American Society of Agricultural and BiologicalEngineers, Vol. 51(2):603-613, 2008). While Bennet and Annex were awareof direct production of ethanol in ensilage inoculated with yeast, theyconcluded that such direct production method was impractical because ofissues related to separating ethanol from silage, ensilage storagelosses (up to 40% in bunker style silos), and the possible use of silageas an alternative fermentation feedstock have yet to be examined forindustrial-scale applications.

Shen and Liu sought to address the long-time and effective storage offresh stalk or juice by first dried the sweet sorghum in order topreserve the sugars, then plan to use the material year-round forethanol production, thereby adding costs of material handling fordrying, spreading the wet sorghum for drying, as well as addingrestrictions to the process by requiring adequate weather conditions toachieve proper drying (see Research on Solid-State Ethanol FermentationUsing Dry Sweet Sorghum Stalk Particles with Active Dry Yeast, Shen, Feiand Liu, R., Energy & Fuels, 2009, Vol. 23, pgs. 519-525). Imam andCapareda sought to process the juice before fermentation and to increasethe fermentation rates using a variety of options such as autoclave(heat treat), freeze, and to increase the sugar concentration (seeEthanol Fermentation from Sweet Sorghum Juice, Imam, T. and Capareda,S., ASABE, 2010 ASABE Annual International Meeting, Pittsburge, Pa.(June 2010)).

Bellmer, Huhnke, and Godsey noted challenges to using sorghum in ethanolproduction as: (i) storability of carbohydrates in sweet sorghum, (ii)quick sugar/carbohydrate degradation in-stalk after harvest, (iii) shortshelf life of expressed juice, (iv) syrup production (dewatering) toocostly (see The untapped potential of sweet sorghum as a bioenergyfeedstock, Bellmer, D., Huhnke, R., and Godsey, C., Biofuels 1(4)563-573, 2010). They used a solid phase fermenter, which are metalliccontainers including rotary drums and screw augers, which requireexpensive equipment. Further, use of a solid phase fermenter is alsosubject to the harvest window of the crop, e.g., sweet sorghum.Likewise, Noah and Linden noted storability and inefficient sugarextraction as the two major drawbacks to sweet sorghum use for fuels andchemicals.

In summary, obstacles in using sorghum and other plants containingfermentable sugars include the fact that they are only seasonallyavailable and storage is costly, which make it challenging to useinfrastructure efficiently and to schedule labor; sugar extraction andstorability are two critical obstacles because conversion must bestarted immediately after harvest to avoid spoilage.

Thus, there is a need for a process to produce ethanol and othervolatile organic compounds on a large scale from biomass material thataddresses at least these obstacles, such as preferably not competingwith the world's food source.

SUMMARY

Embodiments of the present invention provide a number of advantages overconventional processes. Embodiments of the invention allow foreconomical production of ethanol and other volatile organic compoundsfrom plants that contain fermentable sugar by addressing the challenges,some of which noted above, such as needs of decentralized plants, shortharvest windows, quick degradation of sugars, and large investment inequipment.

In certain embodiments, fermentation may be achieved by storing theprepared biomass material in one or more piles, thereby reducing oreliminating the need for expensive equipment as compared to the priorart fermentation process which generally requires significant capitalinvestment. Embodiments of the invention allow for fermentation inconjunction with product storage where prior art fermentation offermentable sugar crops often requires just-in-time harvesting to avoidspoilage, which makes the prior art operation time sensitive.

Embodiments of the invention allow for the recovery facility to runcontinuously year-round in a controlled manner independent of theharvest window, thereby broadening the geological locations available toplace a recovery facility, including areas with a relatively shortharvest window. For example, sugar cane ethanol plants in Braziltypically operate about nine months a year because that is the harvestwindow for sugar cane in Brazil. In the U.S., the same plant could onlyoperate about three to five months per year because of the requirementfor just in time harvest coupled with the short time of cropavailability. Embodiments of the present invention eliminate or minimizethe need for just-in-time harvesting allowing for year-round ethanolproduction regardless of the harvest window of the sugar crop.

Embodiments of the invention provide control over the period offermentation and storage where there is minimal degradation of thevolatile organic compounds for up to 700 days, thereby allowing for ashort harvest window where the crop is closest to its peak sugarpotential and field yield. This allows for harvesting at the optimalcondition rather than conventional processes that may need to compromisethe level of sugar production and field yield to obtain a longerharvesting window.

Further, embodiments of the invention allow for large scale productionof ethanol or other volatile organic compounds, including recovery ofsufficient amounts for commercialization or other industrialapplications.

In a particular embodiment, there is provided a method for producing atleast one volatile organic compound comprising: generating at leastabout 10 tons of prepared biomass material comprising at least oneadditive added to a solid biomass comprising a sugar, wherein said atleast one additive comprise a microbe, and optionally, an acid and/or anenzyme; storing the prepared biomass material for at least about 24hours in a storage facility to allow for the production of at least onevolatile organic compound from at least a portion of the sugar; andcapturing the at least one volatile organic compound by feeding thestored biomass material to a solventless recovery system to separate thestored biomass material into at least a gas component comprising the atleast one volatile organic compound and a solid component.

In one embodiment, the capturing step comprises: introducing theprepared biomass material to an enclosed compartment of a solventlessrecovery system, wherein the prepared biomass material contains one ormore volatile organic compounds; contacting the prepared biomassmaterial with a superheated vapor stream in the enclosed compartment tovaporize at least a portion of an initial liquid content in the preparedbiomass material, said superheated vapor stream comprising at least onevolatile organic compound; separating a gas component and a solidcomponent from the prepared biomass material, said gas componentcomprising at least one volatile organic compound; and retaining atleast a portion of the gas component for use as part of the superheatedvapor stream.

In another embodiment, there is provided a method for producing astorable wet biomass containing volatile organic compounds, said methodcomprising: adding at least one additive to at least about 10 tons of asolid biomass to generate a prepared biomass material, said solidbiomass comprising a sugar-producing plant, wherein said at least oneadditive comprise a microbe, and optionally, an acid and/or an enzyme;and allowing conversion of at least a portion of the sugar in theprepared biomass material into a volatile organic compound; wherein thebiomass material is capable of being stored for about 700 days withoutsignificant degradation of the volatile organic compound.

In addition to the features described above, embodiments of theinvention allow for economical production of alternative fuels, such asethanol and other volatile organic compounds, from plants that containfermentable sugar by addressing challenges, such as costs of storage andtransportation, short harvest windows, quick degradation of sugars, andlarge investment in equipment. Aspects of the embodiments describedherein are applicable to any biomass material, such as plants containingfermentable sugars. The features of embodiments of the present inventionallow for economical use of various plants to produce alternative fuelsand chemicals and are not limited to sorghum and other plants thatsuffer similar challenges. Such challenging crops are highlighted hereinbecause other methods and systems have not been able to economically usethese challenging crops to produce fuels and chemicals. As such, thespecific mention of sorghum is not intended to be limiting, but ratherillustrates one particular application of embodiments of the invention.

Other features and advantages of embodiments of the present inventionwill become apparent from the following detailed description. It shouldbe understood, however, that the detailed description and the specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings illustrate certain aspects of some of the embodiments ofthe invention, and should not be used to limit or define the invention.

FIG. 1 is a diagram of one embodiment to process biomass materialaccording to certain aspects of the present invention.

FIG. 2 is a diagram of another embodiment to process biomass materialaccording to certain aspects of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments of the present invention provide for efficient andeconomical production and recovery of ethanol or other volatile organiccompounds, such as acetic acid, from solid biomass material,particularly on a larger scale, such as on the commercialization orindustrial scale. According to one aspect of the invention, the methodcomprises (a) generating at least about 10 tons of prepared biomassmaterial by adding a microbe, optionally an acid, and optionally, anenzyme to a solid biomass; (b) storing the prepared biomass material forat least about 24 hours in a storage facility to allow production of atleast one volatile organic compound from at least a portion of the sugarin the solid biomass; and (c) capturing the at least one volatileorganic compound by using a solventless recovery system.

As used herein, the term “solid biomass” or “biomass” refers at least tobiological matter from living, or recently living organisms. Solidbiomass includes plant or animal matter that can be converted intofibers or other industrial chemicals, including biofuels. Solid biomasscan be derived from numerous types of plants or trees, includingmiscanthus, switchgrass, hemp, corn, tropical poplar, willow, sorghum,sugarcane, sugar beet, and any energy cane, and a variety of treespecies, ranging from eucalyptus to oil palm (palm oil). In oneembodiment, the solid biomass comprises at least one fermentablesugar-producing plant. The solid biomass can comprise two or moredifferent plant types, including fermentable sugar-producing plant. Thedifferent plant types can have the same or different harvest season. Ina preferred embodiment not intended to limit the scope of the invention,sorghum is selected, due to its high-yield on less productive lands andhigh sugar content.

The term “fermentable sugar” refers to oligosaccharides andmonosaccharides that can be used as a carbon source (e.g., pentoses andhexoses) by a microorganism to produce an organic product such asalcohols, organic acids, esters, and aldehydes, under anaerobic and/oraerobic conditions. Such production of an organic product can bereferred to generally as fermentation. The at least one fermentablesugar-producing plant contains fermentable sugars dissolved in the waterphase of the plant material at one point in time during its growthcycle. Non-limiting examples of fermentable sugar-producing plantsinclude sorghum, sugarcane, sugar beet, and energy cane. In particular,sugarcane, energy cane, and sorghum typically contain from about 5% toabout 25% soluble sugar w/w in the water phase and have moisture contentbetween about 60% and about 80% on a wet basis when they are near or attheir maximum potential fermentable sugar production (e.g., maximumfermentable sugar concentration).

The term “wet basis” refers at least to the mass percentage thatincludes water as part of the mass. In a preferred embodiment, the sugarproducing plant is sorghum. Any species or variety of the genus sorghumthat provides for the microbial conversion of carbohydrates to volatileorganic compounds (VOCs) can be used. For embodiments using sorghum, theplant provides certain benefits, including being water-efficient, aswell as drought and heat-tolerant. These properties make the cropsuitable for many locations, including various regions across the earth,such as China, Africa, Australia, and in the US, such as portions of theHigh Plains, the West, and across the South. Texas.

In embodiments using sorghum, the sorghum can include any variety orcombination of varieties that may be harvested with higherconcentrations of fermentable sugar. Certain varieties of sorghum withpreferred properties are sometimes referred to as “sweet sorghum.” Thesorghum can include a variety that may or may not contain enoughmoisture to support the juicing process in a sugar cane mill operation.In a preferred embodiment, the solid biomass includes a Sugar T sorghumvariety commercially produced by Advanta and/or a male parent of SugarT, which is also a commercially available product of Advanta. In apreferred embodiment, the crop used has from about 5 to about 25 brix,preferably from about 10 to about 20 brix, and more preferably fromabout 12 to about 18 brix. The term “brix” herein refers at least to thecontent of glucose, fructose, and sucrose in an aqueous solution whereone degree brix is 1 gram of glucose, fructose, and/or sucrose in 100grams of solution and represents the strength of the solution aspercentage by weight (% w/w). In another preferred embodiment, themoisture content of the crop used is from about 50% to 80%, preferablyat least 60%.

In one embodiment, the crop is a male parent of Sugar T with a brixvalue of about 18 and a moisture content of about 67%. In anotherembodiment, the crop is Sugar T with a brix value of about 12 at amoisture content of about 73%. In these particular embodiments, the brixand moisture content values were determined by handheld refractometer.

After at least one additive (a microbe, optionally, an acid and/orenzyme) is added to the solid biomass, it becomes prepared biomassmaterial where the at least one additive facilitates the conversion offermentable sugar into a VOC (such as ethanol). As noted above andfurther described below, the prepared biomass material can be stored fora certain period of time to allow more VOCs to be generated by theconversion process. At least one volatile organic compound is thenrecovered from the prepared biomass material. Volatile organic compoundsare known to those skilled in the art. The U.S. EPA providesdescriptions volatile organic compounds (VOC), one of which is anycompound of carbon, excluding carbon monoxide, carbon dioxide, carbonicacid, metallic carbides or carbonates, and ammonium carbonate, whichparticipates in atmospheric photochemical reactions, except thosedesignated by EPA as having negligible photochemical reactivity (seehttp://www.epa.gov/iaq/voc2.html#definition). Another description ofvolatile organic compounds, or VOCs, is any organic chemical compoundwhose composition makes it possible for them to evaporate under normalindoor atmospheric conditions of temperature and pressure. This is thegeneral definition of VOCs that is used in the scientific literature,and is consistent with the definition used for indoor air quality.Normal indoor atmospheric conditions of temperature and pressure referto the range of conditions usually found in buildings occupied bypeople, and thus can vary depending on the type of building and itsgeographic location. One exemplary normal indoor atmospheric conditionis provided by the International Union of Pure and Applied Chemistry(IUPAC) and the National Institute of Standards and Technology (NIST).IUPAC's standard is a temperature of 0° C. (273, 15 K, 32° F.) and anabsolute pressure of 100 kPa (14.504 psi), and NIST's definition is atemperature of 20° C. (293, 15 K, 68° F.) and an absolute pressure of101.325 kPa (14.696 psi).

Since the volatility of a compound is generally higher the lower itsboiling point temperature, the volatility of organic compounds aresometimes defined and classified by their boiling points. Accordingly, aVOC can be described by its boiling point. A VOC is any organic compoundhaving a boiling point range of about 50 degrees C. to 260 degrees C.measured at a standard atmospheric pressure of about 101.3 kPa. Manyvolatile organic compounds that can be recovered and/or furtherprocessed from VOCs recovered from embodiments of the present inventionhave applications in the perfume and flavoring industries. Examples ofsuch compounds may be esters, ketones, alcohols, aldehydes, hydrocarbonsand terpenes. The following Table 1 further provides non-limitingexamples of volatile organic compounds that may be recovered and/orfurther processed from VOCs recovered from the prepared biomassmaterial.

TABLE 1 Methanol Ethyl acetate Acetaldehyde Diacetyl 2,3-pentanedioneMalic acid Pyruvic acid Succinic acid Butyric acid Formic acid Aceticacid Propionic acid Isobutyric acid Valeric acid Isovaleric acid2-methylbutyric Hexanoic acid Heptanoic acid Octanoic acid acid Decanoicacid Propanol Isopropanol Nonanoic acid Isobutanol Isoamyl alcoholHexanol Butanol Tryptoptanol Phenethyl alcohol 2,3-butanediol TyrosolFumaric acid Ethanol Amyl alcohol Glycerol 1-propanol 2-butanol Methylacetate 1,2-propanol Propyl acetate Ethyl lactate Propyl lactate Ethylacetate Ethyl formate n-propyl alcohol 2-methyl-1- Acetone 2,3-methyl-1-3-buten-2-ol propanol 2-propen-1-ol butanol

Ethanol is a preferred volatile organic compound. As such, many examplesspecifically mention ethanol. This specific mention, however, is notintended to limit the invention. It should be understood that aspects ofthe invention also equally apply to other volatile organic compounds.Another preferred volatile organic compound is acetic acid.

Embodiments of the present invention provide for the long term storageof solid biomass material without significant degradation to thevolatile organic compounds contained in the prepared biomass material,and they provide for sugar preservation to allow for continuedgeneration of VOCs. As used in this context, “significant” refers atleast to within the margin of error when measuring the amount orconcentration of the volatile organic compounds in the prepared biomassmaterial. In one embodiment, the margin of error is about 0.5%.

Accordingly, embodiments of the present invention allow for continuousproduction VOCs without dependence on the length of the harvest, therebyeliminating or minimizing down time of a recovery plant in traditionaljust-in-time harvest and recovery processes. As such, embodiments of thepresent invention allow for harvest of the crop at its peak withoutcompromises typically made to lengthen the harvest season, such asharvest slightly earlier and later than peak time. That is, embodimentsof the invention allow for harvest at high field yields and high sugarconcentrations, such as when the selected crop has reached its peaksugar concentration or amount of fermentable sugars that can beconverted into a volatile organic compound, even if this results in ashorter harvest period. In one embodiment, the solid biomass isharvested or prepared when it is at about 80%, about 85%, about 90%,about 95%, or about 100% of its maximum potential fermentable sugarconcentration. As such, embodiments of the present invention,particularly the recovery phase, can be operated continuously year-roundwithout time pressure from fear of spoilage of the solid biomass andVOCs contained therein. While embodiments of the present invention allowfor harvest of the solid biomass near or at its maximum sugar productionpotential, the solid biomass material can be harvested at any point whenit is deemed to contain a suitable amount of sugar. Further, the harvestwindow varies depending on the type of crop and the geographicallocation. For example, the harvest window for sorghum in North Americacan range from about 1 to 7 months. However, in Brazil and otherequatorial and near equatorial areas, the harvest window may be up totwelve months.

In embodiments using plants as the solid biomass, the solid biomass canbe collected or harvested from the field using any suitable means knownto those skilled in the art. In one embodiment, the solid biomasscomprises a stalk component and a leaf component of the plant. Inanother embodiment, the solid biomass further comprises a graincomponent. In a preferred embodiment, the solid biomass is harvestedwith a forage or silage harvester (a forage or silage chopper). A silageor forage harvester refers to farm equipment used to make silage, whichis grass, corn or other plant that has been chopped into small pieces,and compacted together in a storage silo, silage bunker, or in silagebags. A silage or forage harvester has a cutting mechanism, such aseither a drum (cutterhead) or a flywheel with a number of knives fixedto it, which chops and transfers the chopped material into a receptaclethat is either connected to the harvester or to another vehicle drivingalongside. A forage harvester is preferred because it provides benefitsover a sugar cane harvester or dry baled system. For example, a forageharvester provides higher density material than a sugar cane harvester,thereby allowing for more efficient transportation of the harvestedmaterial. In one embodiment, using a forage harvester results inharvested sorghum with a bulk density of about 400 kg/m³, compared tosugarcane harvested with a sugarcane harvester with density of about 300kg/m³, and for sorghum harvested with a sugarcane harvester with adensity of about 200 kg/m³. In general, higher bulk density material ischeaper to transport, which tends to limit the geographical area inwhich cane-harvested crop can be sourced.

Thus, a forage harvester is an overall less expensive way to harvest theselected biomass, such as sorghum, than a cane harvester or dry baledsystem. Not to be bound by theory, it is believed the cost savings aredue in part to higher material throughputs and the higher bulk densityof the solid biomass harvested by a forage harvester. The solid biomasscan be cut in any length. In one embodiment, the chop lengths of theharvester can be set to a range of about 3 mm to about 80 mm, preferablyabout 3 mm to about 20 mm, with examples of about 3 mm to about 13 mmchop lengths being most preferred. At these preferred chop lengths,there was not observable aqueous discharge in the forage harvester, solosses were minimal. When a chop length is selected, the harvesterprovides biomass with an average size or length distribution of aboutthe chop length selected. In one embodiment, the average sizedistribution of the solid component exiting the recovery system can beadjusted as desired, which can be done by adjusting the chop length ofthe harvester.

At least one additive is added to the solid biomass to facilitate and/orexpedite the conversion of appropriate carbohydrates into volatileorganic compounds. After selected additive(s) have been added, the solidbiomass can be referred to as prepared biomass material. In oneembodiment, the prepared biomass material can comprise at least one orany combination of fermentable sugar-producing plants listed above. In apreferred embodiment, the selected additive(s) can be conveniently addedusing the harvester during harvest.

Embodiments of the invention provide for a scaled up operation togenerate at least about 10 tons of the prepared biomass material in aparticular harvest period. For embodiments using a forage harvester, theforage harvester assists in achieving the scaled up amount. In oneembodiment, at least about 700 tons, preferably at least about 1 milliontons, such as at least 1.2 million tons, or more preferably about atleast 5 million tons of prepared biomass material is generated in aparticular harvest window based on the growing conditions of a specificregion, such as about 1 to 7 months in North America for sorghum. In oneembodiment, up to 100 million tons of prepared biomass are generated ina particular harvest period.

The at least one additive can be added at any point during and/or afterthe harvest process. In a preferred embodiment using a forage harvester,additives are added to the solid biomass during the harvest process togenerate a prepared biomass material. In particular, forage harvestersare designed for efficiently adding both solid and liquid additivesduring harvest. As mentioned above, the additives added include at leasta microbe (e.g. a yeast), and optionally, an acid and/or an enzyme. In apreferred embodiment, the selected additive(s) are added as solutions.Additional details of the potential additives are further providedbelow.

For embodiments using a forage harvester or a similar equipment, theselected additive(s) can be added during harvest at all phases, such asbefore the intake feed rollers, during intake, at chopping, afterchopping, through the blower, after the blower, in the accelerator, inthe boom (or spout), and/or after the boom. In one embodiment where acidand enzyme are added, the acid is added near the intake feed rollers,and a microbe and the enzyme are added in the boom. In a particularembodiment, a Krone Big X forage harvester with a V12 motor with anabout 30 ft wide header is used. In an embodiment using the Kronesystem, the acid is added as a solution through flexible tubing thatdischarged the solution just in front of the feed rollers. In this way,the liquid flow can be visually monitored, which showed the acidsolution and solid biomass quickly mixed inside the chopping chamber. Inanother embodiment, the addition of acid was also demonstrated as aviable practice using a Case New Holland FX 58 forage harvester. Incertain embodiments, the forage harvester used can include an onboardrack for containing additives, at least the one(s) selected to be addedduring harvest. In another embodiment, the selected additive(s) to beadded during harvest may be towed behind the harvester on a trailer. Forexample, in one embodiment, it was demonstrated that a modified utilitytrailer equipped with tanks containing additive solutions of yeast,enzymes and acid can be employed with minimal interfering with normaloperations of the harvester, thereby substantially maintaining theexpected cost and duration of the harvest process. For example, a normalharvest configuration and biomass yield employing a silage harvestertravelling at about 4 miles per hour maintains a similar rate ofcollection of about 4 miles per hour when equipped with certainadditives as described above in one embodiment.

In embodiments of the present invention, the prepared biomass materialis eventually transported to a storage facility where it is stored for aperiod of time to allow for production of at least one volatile organiccompound from at least a portion of the fermentable sugar of the solidbiomass. The details of the storage phase are further provided below. Incertain embodiments, selected additive(s) can also be added at thestorage facility. For example, in one embodiment, the selectedadditive(s) can be added during unloading or after the solid biomass hasbeen unloaded at the storage facility. In one embodiment, a conveyancesystem is used to assist with the adding of selected additive(s) at thestorage facility. Additive(s) added at the storage facility to solidbiomass can be one(s) that have not been added or additional amount ofone(s) previously added. Accordingly, selected additive(s) can thereforebe added at any point from the start of the harvest process to prior tostorage of the prepared biomass material at the storage area orfacility, such as at points where the material is transferred.

As mentioned above, additive(s) for embodiments of the present inventioninclude at least a microbe and optionally, an acid and/or an enzyme.Selected additive(s) can be added to the solid biomass in any order. Ina preferred embodiment, an acid is added to the solid biomass beforeadding a microbe to prime the material to provide an attractive growthenvironment for the microbe.

In a preferred embodiment, acid is added to reduce the pH of the solidbiomass to a range that facilitates and/or expedites selected indigenousor added microbial growth, which increases production of ethanol and/orvolatile organic compounds. The acid can also stop or slow plantrespiration, which consumes fermentable sugars intended for subsequentVOC production. In one embodiment, acid is added until the pH of thesolid biomass is between about 2.5 and about 5.0, preferably in a rangeof about 3.7 to about 4.3, and more preferably about 4.2. The acid usedcan include known acids, such as sulfuric acid, formic acid, orphosphoric acid. The following Table 2 provides non-limiting examples ofan acid that can be used individually or in combination.

TABLE 2 Sulfuric Acid Formic Acid Propionic Acid Malic Acid PhosphoricAcid Maleic Acid Folic Acid Citric Acid

In a preferred embodiment, after the solid biomass has reached thedesired pH with the addition of acid, a microbe is added. A microbe inthe additive context refers at least to a living organism added to thesolid biomass that is capable of impacting or affecting the preparedbiomass material. One exemplary impact or effect from added microbe(s)includes providing fermentation or other metabolism to convertfermentable sugars from various sources, including cellulosic material,into ethanol or other volatile organic compounds. Another exemplaryimpact or effect may be production of certain enzyme(s) that help todeconstruct cellulose in the prepared biomass material into fermentablesugars which can be metabolized to ethanol or other VOC. Yet anotherexemplary impact or effect provided by a microbe includes production ofcompounds such as vitamins, co-factors, and proteins that can improvethe quality, and thus value, of an eventual by-product that can serve asfeed for animals. Further, microbial activity provides heat for thepile. Parts of the microbial cell walls or other catabolite or anabolitemay also offer value-added chemicals that may be recovered by a recoveryunit. These impacts and effects may also be provided by microbesindigenous to the solid biomass.

Any microbe that is capable of impacting or affecting the preparedbiomass material can be added. In a preferred embodiment, the microbe(s)can include microbes used in the silage, animal feed, wine, andindustrial ethanol fermentation applications. In one embodiment, themicrobe selected includes yeast, fungi, and bacteria according toapplication and the desired profile of the organic molecule to be made.In a preferred embodiment, yeast is the selected microbe. In anotherembodiment, bacteria can be added to make lactic acid or acetic acid.Certain fungi can also be added to make these acids. For example,Acetobacterium acetii can be added to generate acetic acid;Lactobacillus, Streptococcus thermophilus can be added to generatelactic acid; Actinobacillus succinogenes, Mannheimia succiniciproducens,and/or Anaerobiospirillum succiniciproducens can be added to generatesuccinic acid; Clostridium acetobutylicum can be added to generateacetone and butanol; and/or Aerobacter aerogenes can be added togenerate butanediol.

The following Table 3 provides non-limiting examples of preferredmicrobes, which can be used individually or in combination.

TABLE 3 Saccharomyces Saccharomyces Saccharomyces Saccharomycescerevisiae japonicas bayanus fermentatti Saccharomyces SaccharomycesClostridium Clostridium exiguous chevalieri acetobutylicumamylosaccharobutyl propylicum Clostridium propyl- ClostridiumClostridium Aerobacter species butylicum viscifaciens propionicumAerobacter Zymomonas mobilis Zymomonas species Clostridium speciesaerogenes Saccharomyces Bacillus species Clostridium Lactobacillusspecies thermocellum buchneri Lactobacillus Enterococcus Pediococcusspecies Propionibacteria plantarum faecium Acetobacterium StreptococcusLactobacillus Lactobacillus acetii thermophilus paracasei speciesActinobacillus Mannheimia Anaerobiospirillum succinogenessucciniciproducens succiniciproducens

Preferred microbes also include Saccharomyces cerevisiae strains thatcan tolerate high ethanol concentrations and are strong competitors inits respective microbial community. The microbes may be mesophiles orthermophiles. Thermophiles are organisms that grow best at temperaturesabove about 45° C., and are found in all three domains of life:Bacteria, Archaea and Eukarya. Mesophiles generally are active betweenabout 20 degrees C. and 45 degrees C. In an embodiment using a strain ofSaccharomyces cerevisiae, the strain can come from a commerciallyavailable source such as Biosaf from Lesaffre, Ethanol Red from Phibro,and Lallamand activated liquid yeast. If the microbe is obtained from acommercial source, the microbe can be added according to the recommendedrate of the provider, which is typically based on the expected sugarcontent per wet ton, where water is included in the mass calculation.The term “wet ton” refers at least to the mass unit including water. Therecommended amount can be adjusted according to reaction conditions. Themicrobe added can comprise one strain or multiple strains of aparticular microbe. In one embodiment, the microbes are added at a rateof up to 500 mL per wet ton of solid biomass. In a particular embodimentusing commercially available yeast, about 300 mL of Lallamand yeastpreparation is added per wet ton of solid biomass. In anotherembodiment, an additional yeast strain can be added. For example,Ethanol Red can be added at a rate between about 0.001 kg/wet ton toabout 0.5 kg/wet ton, particularly about 0.1 kg/wet ton. In yet anotherembodiment, another yeast strain can be added, e.g., Biosaf, at a ratebetween about 0.001 kg/wet tone to about 0.5 kg/wet ton, particularlyabout 0.1 kg/wet ton. It is understood that other amounts of any yeaststrain can be added. For example, about 10%, about 20%, about 30%, about40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 1.5times, about 2 times, about 2.5 times, or about 3 times of the providedamounts of microbes can be added.

In certain embodiments, an enzyme is further added. The enzyme can beone that assists in the generation of fermentable sugars from plantmaterials that are more difficult for the microbe to metabolize, such asdifferent cellulosic materials, and/or to improve the value of aneventual by-product serving as animal feed, such as by making the feedmore digestable. The enzyme can also be an antibiotic, such as alysozyme as discussed further below. The enzyme added can include onetype of enzyme or many types of enzymes. The enzyme can come fromcommercially available enzyme preparations. Non-limiting examples ofenzymes that assist in converting certain difficult to metabolize plantmaterials into fermentable sugars include cellulases, hemicellulases,ferulic acid esterases, and/or proteases. Additional examples alsoinclude other enzymes that either provide or assist the provision forthe production of fermentable sugars from the feedstock, or increase thevalue of the eventual feed by-product.

In certain embodiments, the enzymes that assist in converting certaindifficult to metabolize plant materials into fermentable sugars can beproduced by the plant itself, e.g. in-plantae. Examples of plants thatcan produce cellulases, hemicellulases, and other plant-polymerdegrading enzymes may be produced within the growing plants aredescribed in the patent publications and patent WO2011057159,WO2007100897, WO9811235, and U.S. Pat. No. 6,818,803, which show thatenzymes for depolymerizing plant cell walls may be produced in plants.In another embodiment, ensilagement can be used to activate such plantproduced enzymes as well as temper the biomass for further processing.One example is described in patent publication WO201096510. If used,such transgenic plants can be included in the harvest in any amount. Forexample, certain embodiments may employ in-plantae enzymes produced inplants by using particular transgenic plants exclusively as a feedstock,or incorporating the transgenic plants in an interspersed manner withinlike or different crops.

In certain embodiments that include such plant-polymer degradingenzymes, ethanol can be produced from cellulosic fractions of the plant.In a particular embodiment, when Novazymes CTEC2 enzyme was added to asorghum storage system in excess of the recommended amount, about 100times more than the recommended amount, about 152% of the theoreticalethanol conversion efficiency based on the initial free sugar contentwas achieved. While such an amount of enzymes can be added usingcommercially available formulations, doing so can be costly. On theother hand, such an amount of enzymes can be obtained in a more costeffective manner by growing transgenic plants that produce these enzymesat least interspersingly among the biomass crop.

The ethanol production from cellulose occurred during the storage phase,e.g., in silage and was stable for about 102 days of storage, afterwhich the experiment was terminated. This demonstrates that, under theconditions of that particular experiment, an excess of such enzymeactivity results in at least about 52% production of ethanol usingfermentable sugars from cellulose. Not intended to be bound by theory,for certain embodiments, the immediate addition of acid during harvestin the experiment may have lowered the pH, thereby potentially inducingthe enzyme activity, which otherwise could damage the plants if producedwhile the plants were still growing.

In a preferred embodiment, if an enzyme is added, the enzyme can be anyfamily of cellulase preparations. In one embodiment, the cellulosepreparation used is Novozymes Cellic CTec 2 or CTec 3. In anotherembodiment, a fibrolytic enzyme preparation is used, particularly,Liquicell 2500. If used, the amount of enzyme added to degrade plantpolymer can be any amount that achieves the desired conversion of plantmaterial to fermentable sugar, such as the recommended amount. In aparticular embodiment, about 80,000 FPU to about 90,000,000 FPU,preferably about 400,000 FPU to about 45,000,000 FPU, more preferablyabout 800,000 FPU to about 10,000,000 FPU of enzyme is added per wet tonof biomass. The term “FPU” refers to Filter Paper Unit, which refers atleast to the amount of enzyme required to liberate 2 mg of reducingsugar (e.g., glucose) from a 50 mg piece of Whatman No. 1 filter paperin 1 hour at 50° C. at approximately pH 4.8.

In certain other embodiments, selected additive(s) added can includeother substances capable of slowing or controlling bacterial growth.Non-limiting examples of these other substances include antibiotics(including antibiotic enzymes), such as Lysovin (lysozyme) and Lactrol®(Virginiamycin, a bacterial inhibitor). Control of bacterial growth canallow the appropriate microbe to expedite and/or provide the productionof volatile organic compounds. Antibiotic is a general term forsomething which suppresses or kills life. An example of an antibiotic isa bacterial inhibitor. In one embodiment, a selective antibiotic that isintended to impact bacteria and not other microbes is used. One exampleof a selective antibiotic is Lactrol, which affects bacteria but doesnot affect yeasts.

In a particular embodiment, if used, Lactrol can be added at rates ofabout 1 to 20 part-per-million (ppm) w/v (weight Lactrol per volumeliquid) as dissolved in the water phase of the prepared biomassmaterial, for example at about at about 5 ppm w/v. In an embodimentusing an enzyme to control bacterial growth, lysozyme is preferablyused. The lysozyme can come from a commercial source. An exemplarycommercially available lysozyme preparation is Lysovin, which is apreparation of the enzyme lysozyme that has been declared permissiblefor use in food, such as wine.

The enzyme and/or other antibiotic material, if used, can be addedindependently or in conjunction with one another and/or with themicrobe. In certain embodiments, other compounds serving as nutrients tothe microbes facilitating and/or providing the volatile organic compoundproduction can also be added as an additive. The following Table 4provides non-limiting examples of other substances, includingantibiotics, which can be added to the solid biomass.

TABLE 4 Potassium Potassium FermaSure ® (from Lysovin MetabisulfiteBicarbonate Dupont ™) - oxychlorine products including chlorite ThiaminMagnesium Calcium Diammonium Sulfate Pantothenate Phosphate AmmoniaAntibiotics Lactrol Biotin

Yeasts and other microbes that are attached to solids individually, assmall aggregates, or biofilms have been shown to have increasedtolerance to inhibitory compounds. Not intended to be bound by theory,part of the long-term fermentation may be possible or enhanced by suchmicrobial-to-solids binding. As such, the prepared biomass material thatincludes the microbe optimized for microbial binding as well asadditives that may bind microorganisms can experience a greater extentof fermentation and or efficiency of fermentation. Substances providingand/or facilitating long term fermentation is different from substancesthat increase the rate of fermentation. In certain embodiments, anincrease in the rate of fermentation is not as an important factor asthe long-term fermentation, particularly over a period of many weeks ormonths.

The following provides particular amounts of additives applied to onespecific embodiment. If used, the rate and amount of adding an acidvaries with the buffering capacity of the particular solid biomass towhich the particular acid is added. In a particular embodiment usingsulfuric acid, 9.3% w/w sulfuric acid is added at rates of up to about10 liter/ton wet biomass, for example at about 3.8 liter/ton wet biomassto achieve a pH of about 4.2. In other embodiments, the rate will varydepending on the concentration and type of acid, liquid and othercontent and buffering capacity of the particular solid biomass, and/ordesired pH. In this particular embodiment, Lactrol is added at a rate ofabout 3.2 g/wet ton of solid biomass. Yeasts or other microbes are addedaccording to the recommended rate from the provider, such as accordingto the expected sugar content per wet ton. In one particular embodiment,Lallemand stabilized liquid yeast is added at about 18 fl oz per wetton, and Novozymes Cellic CTec2 is added at about 20 fl oz per wet ton.

In a preferred embodiment, selected additive(s) are added to the solidbiomass stream during harvest according to aspects of the inventiondescribed above to generate the prepared biomass material. Preferably,the prepared biomass material is transported to a storage facility toallow for conversion of carbohydrates of the prepared biomass materialinto volatile organic compounds of the desired amount and/or awaitrecovery of the volatile organic compounds. Any suitable transportationmethod and/or device can be used, such as vehicles, trains, etc, and anysuitable method to place the prepared biomass material onto thetransportation means. Non-limiting examples of vehicles that can be usedto transport the biomass material include end-unloading dump trucks,side-unloading dump trucks, and self-unloading silage trucks. In apreferred embodiment, a silage truck is used. In embodiments using aforage harvester to collect the biomass, transportation of such solidbiomass is more efficient than transportation of materials collected byconventional means, such as sugar cane billets, because the bulk densityis higher in the solid biomass cut with a forage harvester. That is,materials chopped into smaller pieces pack more densely than materialsin billets. In one embodiment, the range of bulk densities in a silagetruck varies between about 150 kg/m³ and about 350 kg/m³, for exampleabout 256 kg/m³. Because in certain embodiments, all selected additivesare added during harvest, preferably on the harvester, the microbe maybegin to interact with the biomass during transportation, and in thisway transportation is not detrimental to the overall process.

-   -   The biomass, whether prepared or not, is delivered to at least        one storage area or facility. The storage facility can be        located any distance from the harvest site. Selected additive(s)        can be added if they have not been added already or if        additional amounts or types need to be further added to generate        the prepared biomass material. In a preferred embodiment, the        prepared biomass is stored in at least one pile on a prepared        surface for a period of time. The facility can incorporate        man-made or natural topography. Man-made structures can include        existing structures at the site not initially designated for        silage, such as canals and water treatment ponds. Non-limiting        examples of a prepared surface includes a concrete, asphalt, fly        ash, or soil surface. The at least one pile can have any        dimension or shape, which can depend on operating conditions,        such as space available, amount of biomass, desired storage        duration, etc.

In a particular embodiment, at least one pile of prepared biomassmaterial is formed having a height in a range of about 10 feet to about30 feet. In another embodiment, the height of the at least one pile isgreater than 30 feet. In one embodiment, at least one pile of preparedbiomass material contains at least about 10 tons of prepared biomassmaterial, which can be wet tons. In another embodiment, at least onepile contains 25,000 tons (or wet tons) of prepared biomass material. Inanother embodiment, the at least one pile of prepared biomass materialcontains at least about 100,000 tons (or wet tons) of prepared biomassmaterial. In yet another embodiment, the least one pile of preparedbiomass material contains at least about 1,000,000 tons or (wet tons),such as 1,200,000 wet tons, of prepared biomass material. In oneembodiment, the at least one pile contains up to about 10,000,000 tons,and in another embodiment, up to 100,000,000 tons (or wet tons) ofprepared biomass material.

The conversion process of fermentable sugars is an exothermic reaction.Too much heat, however, can be detrimental to the conversion process ifthe temperature is in the lethal range for the microbes in the preparedbiomass material. However, in an embodiment using about 700 wet tons ofbiomass and piling up to about 12 feet, ethanol production and stabilitywere satisfactory. Therefore larger piles will likely not suffer fromoverheating. In one embodiment, an inner portion of the pile maintains atemperature in a range of about 20 degrees C. to about 60 degrees C. formicrobes of all types, including thermophiles. In an embodiment notemploying thermophiles, an inner portion of the pile maintains atemperature in a range of about 35 degrees C. to about 45 degrees C.

The prepared biomass material that is stored as at least one pile at thestorage facility can also be referred to as a wet stored biomassaggregate. After addition of the selected additive(s), at least aportion of the solid biomass is converted to volatile organic compounds,such as fermentation of sugars into ethanol. In one embodiment, theprepared biomass material is stored for a period of time sufficient toachieve an anaerobiasis environment. In a preferred embodiment, theanaerobiasis environment is achieved in about 24 hours. In anotherembodiment, the anaerobiasis environment is achieved in more than about4 hours. In yet another embodiment, the anaerobiasis environment isachieved in up to about 72 hours.

The pile can be free standing or formed in another structure, such as asilage bunker, designed to accept silage, including provisions tocollect aqueous runoff and leachate, placement of a tarp over thebiomass, and to facilitate both efficient initial silage truck unloadinginto the bunker as well as removal of the biomass year around. Theindividual bunkers may be sized at about the size to support annualfeedstock requirements of about 700 wet tons to 100,000,000 wet tons ormore. For example, the storage facility may have 50 bunkers, where eachindividual bunker can accept 100,000 wet tons of prepared biomassmaterial for a total of a maximum of about 5,000,000 wet tons of storedmaterial at any one time. Other exemplary inventory amounts of preparedbiomass material at any one storage facility include at least about 10tons, about 25,000 tons, about 100,000 tons, about 1,000,000 tons, about1,200,000 tons, about 1,500,000 tons, about 10,000,000 tons, and up toabout 100,000,000 tons. In a preferred embodiment where ethanol is thevolatile organic compound of choice, about 14 gallons to about 16gallons of ethanol is recovered per one wet ton of prepared biomassmaterial. The provided numbers are exemplary and not intended to limitthe amount of prepared biomass material a storage facility canaccommodate.

In a particular embodiment, the storage pile further includes a leachatecollection system. In one embodiment, the collection system is used toremove leachate collected from the storage pile. For example, theleachate collection system can be adapted to remove liquid from the pileat certain points during the storage period. In another embodiment, theleachate collection system is adapted to circulate the liquid in thestorage pile. For example, circulation can involve taking at least aportion of the recovered liquid and routing it back to the pile,preferably at or near the top portion. Such recirculation allows forlonger retention time of certain portions of the liquids in the pile,even as the recovery phase of the prepared biomass material begins andportions of the non-liquid component of the prepared biomass materialare sent to the recovery unit. The longer retention time results inlonger microbial reaction time, and hence, higher concentrations oforganic volatile compounds, such as ethanol.

Any suitable leachate collection system known to those skilled in theart can be employed as described. In a particular embodiment, theleachate collection system comprises at least one trough along thebottom of the pile, preferably positioned near the middle, of thestorage pile or bunker if one is used, where the storage pile isprepared at a grade designed to direct liquid from the prepared biomassmaterial to the trough and out to a desired collection receptacle orrouted to other applications.

In another embodiment, the leachate collection system comprises one ormore perforated conduits, preferably pipes made of polyvinyl chloride(PVC), that run along the bottom of the pile to allow the liquidcollected in the conduits to be directed away from the pile.

In one embodiment, as the prepared biomass material is added to thebunker or laid on top of the prepared surface, a tractor or other heavyimplement is driven over the pile repeatedly to facilitate packing. Inone embodiment, the packing ranges from about 7 lbs/ft³ to about 50lbs/ft³ per cubic foot for the prepared biomass material. In a preferredembodiment, the packing is from about 30 lbs/ft³ to about 50 lbs/ft³,particularly about 44 lbs/ft³. In one embodiment, the compacting of theprepared biomass material in a pile facilitates and/or allows ananaerobiasis environment to be achieved in the preferred time periodsdescribed above. In another embodiment, after the packing is performedor during the time the packing is being performed, an air impermeablemembrane is placed on the pile, typically a fit for purpose plastictarp. In a particular embodiment, the tarp is placed on the pile as soonas is practical. For instance, the tar is placed on the pile within a24-hour period.

In one embodiment, the prepared biomass material is stored for at leastabout 24 hours and preferably at least about 72 hours (or 3 days) toallow for production of volatile organic compounds, such as ethanol. Inone embodiment, the prepared biomass material is stored for about threedays, preferably ten days, more preferably greater than ten days. In oneembodiment, the time period for storage of the prepared biomass is about1 day to about 700 days, preferably about 10 to 700 days. In anotherembodiment, the biomass material is stored for up to about three years.In one embodiment, the prepared biomass material is stored for a timeperiod sufficient to allow a conversion efficiency of sugar to at leastone volatile organic compound of at least about 95% of the theoreticalproduction efficiency as calculated through a stoichiometric assessmentof the relevant biochemical pathway. In another embodiment, the preparedbiomass material is stored for a time period sufficient to allow acalculated conversion efficiency of sugar to at least one volatileorganic compound of at least about 100%. In yet another embodiment, theprepared biomass material is prepared with certain additives, such asenzymes, that allow a calculated conversion efficiency of sugar to atleast one volatile organic compound of up to about 150% of thetheoretical value based on the initial amount of available fermentablesugars. Not intended to be bound by theory, it is believed that, at orabove 100% efficiency, the volatile organic compound(s) are producedfrom both the initially available fermentable sugars and fermentablesugars from cellulosic or other polymeric material in the preparedbiomass material, which can be achieved by enzymatic hydrolysis or acidhydrolysis facilitated by certain additive(s) applied to the biomass.

The produced volatile organic products, such as ethanol, remain stablein the stored prepared biomass material for the duration of the storageperiod. In particular, the prepared biomass material can be stored up to700 days without significant degradation to the volatile organiccompounds. “Significant” in this context refers at least to within themargin of error when measuring the amount or concentration of thevolatile organic compounds in the prepared biomass material. In oneembodiment, the margin of error is 0.5%. It has been demonstrated thatethanol remains stable in the pile after at least about 330 days with nosignificant ethanol losses observed. This aspect of embodiments of thepresent invention is important because it provides for at least eightmonths of stable storage, which enables year-round VOCs production andrecovery with a harvest window of only about four months. Embodiments ofthe invention provide significant advantages over the conventionaljust-in-time processing that would only be able to operate during thefour months harvest window per year. That is, embodiments of theinvention allow a plant to operate year-round using only a four-monthharvest window, thereby reducing capitals cost for a plant of the samesize as one used for just-in-time processing.

Also, in an embodiment employing a tarp, it is envisioned that placingsoil or other medium around and on the tarp edges to 1) provide weightfor holding the tarp down; and also 2) to act as a biofilter of theoff-gas from the pile. In such an embodiment, biofilters are efficientfor organics and carbon monoxide detoxification/degradation. Theprepared biomass material can also be stored as compressed modules,drive over piles, bunkers, silos, bags, tubes, or wrapped bales or otheranaerobic storage system.

In one embodiment, the off-gas stream from a pile of prepared biomassmaterial was monitored, and it was found that only small levels oforganics, and also very low levels of nitrogen oxides, were present. Forexample, Tables 5.1, 5.2, and 5.3 below show the analysis of variousoff-gas samples collected during the storage phase of one implementationof certain embodiments of the invention. The designation “BDL” refers toan amount below detectable limit. Summa and Tedlar refer to gas samplingcontainers commercially available.

TABLE 5.1 Container Container % % Normalized type ID % H₂ % O₂ % N₂ CH₄CO₂ % H₂O CO2 Tedlar bag A BDL 1.72 7.84 BDL 95.90 5.23 85.21 Tedlar bagB BDL 2.30 9.12 BDL 89.97 5.97 82.62 Tedlar bag C BDL 0.71 3.57 BDL97.45 5.54 90.18 Tedlar bag D BDL 0.72 3.18 BDL 97.50 5.97 90.14 Tedlarbag E BDL 1.86 7.24 BDL 91.75 7.64 83.26 Summa EQ #8  0.01 5.74 22.140.07 73.74 5.28 66.84 Container Summa EQ #13 0.09 3.28 12.89 0.33 84.485.66 78.18 Container Summa EQ #16 0.12 3.30 13.01 0.12 84.65 4.99 78.70Container

TABLE 5.2 Container Container % ppmv % ppmv ppmv ppmv ppmv ppmv type IDO₂ CO CO₂ HC NO NO₂ NO_(X) SO₂ Tedlar bag A 1.6 13 72.7 104 3.8 1.905.70 BDL Tedlar bag B 4.4 19 66.2 739 2.5 122.90 125.40 6 Tedlar bag C0.6 29 75.3 158 8.9 27.20 36.10 4 Tedlar bag D 0.6 35 75.7 222 7.9 56.5064.40 5 Tedlar bag E 4.1 35 66.8 423 3.0 20.30 23.90 4

TABLE 5.3 Container Container ppmv ppmv ppmv ppmv 2- ppmv ppmv type IDCH2O C2H4O methanol propanol ethanol propanol Tedlar bag A 386 870 63.40.593 78.5 BDL Tedlar bag B BDL 1299 678 0.186 1065 15.2 Tedlar bag C 18.2 590 89.2 2.784 171 6.098 Tedlar bag D BDL 941 170 3.031 264 7.648Tedlar bag E BDL 819 389 2.512 634 11.3

Embodiments of the present invention, although relatively uncontained inthe bunker, should be environmentally benign. Even so, certain aspectsof the present invention fit well with using soil or other media as abiofilter placed around and on the bunkers because the escape of gasfrom under the tarp is radial in nature. As such, the vapors have ahigher amount of surface area in contact with the edges of the pile. Inembodiments using a biofilter, vapor phase releases pass through thebiofilter (such as soil or compost) placed near the edge mass beforeentering into the atmosphere. The biofilter retains many potentialenvironmental pollutants and odors released by the storage pile, and iteliminates or greatly reduces the potentially harmful off-gases releasedfrom the storage pile.

In one embodiment, the prepared biomass material is stored until itcontains no more than about 80 wt % liquid. The prepared biomassmaterial is stored until it contains at least about 4 to about 5% higherthan initial content. At this stage, the wet stored biomass aggregate isnot considered “beer” yet since it still contains over about 20% solids.In one embodiment, the prepared biomass material is stored until itcontains between about 2 wt % and about 50 wt % ethanol, and preferablybetween about 4 wt % and about 10 wt % ethanol. The balance of theliquid is primarily water but can contain many other organic compounds,such as acetic acid, lactic acid, etc.

Embodiments of the present invention allow the solid biomass to beharvested in a much shorter harvest window than typical sugar canejuicing operations, which allows for 1) a much larger geographic areawhere the facilities could be placed,

2) harvest of the crop when the crop has its highest yield potential,

3) harvest of the crop at its highest sugar concentration potential,

4) shorter harvest window still economical, and

5) decoupling the need for taking the juice from the biomass forfermentation.

Moreover, aspects of the present invention allow for larger scaleoperations, such as in the industrial or commercialization range. In oneembodiment, at least about 10 tons of prepared biomass material isgenerated by adding a microbe, an acid, and optionally an enzyme to thesolid biomass. Other amounts are provided above.

The preparation of the biomass material of embodiments of the inventioncan also be generally referred to as solid state fermentation. Once theprepared biomass material has been stored for the desired amount of timeand/or contains a desired concentration of volatile organic compounds,such as ethanol, it can be routed to the recovery system for recovery ofparticular volatile organic compounds. The recovery system and storagefacility can be located any distance from one another. Embodiments ofsystems and methods described herein allow flexibility in thegeographical location of both and their locations relative to eachother. In a particular embodiment, the recovery system is located about0.5 to about 2 miles from the storage facility. Any suitable methodand/or equipment can be used to transfer the prepared biomass materialfrom the storage facility to the recovery system. In one embodiment, afeed hopper is used. In one embodiment, a silage facer, a front endloader or payloader, a sweep auger or other auger system can be used toplace the prepared biomass material into the feed hopper. The materialcan be placed directly into the feed hopper or it can be transferred toby conveyer system, such as belt system. The feed hopper containing theprepared biomass material can then be driven to the recovery system.

The recovery system is solventless and uses a superheated vapor streamto vaporize the liquid in the prepared biomass material into a gascomponent, which can then be collected. A super-heated vapor is a vaporthat is heated above its saturation temperature at the pressure ofoperation. In a preferred embodiment, after the recovery system reachessteady state, the superheated vapor stream comprises only vaporpreviously evaporated from the prepared biomass material, so that noother gas is introduced, thereby reducing the risk of combustion of thevolatile organic compounds and/or dilution of the recovered productstream of volatile organic compounds. The remaining solid component isdischarged from the system and can have various subsequent uses. Aportion of the vapor is removed as product and the remainder is recycledback for use in transferring heat to fresh incoming prepared biomassmaterial. The super-heated vapor directly contacts the biomasstransferring energy and vaporizing the liquid present there. The heat orthermal energy source does not directly contact the prepared biomassmaterial. Thus, the VOC recovery system can also be described asproviding “indirect” heat contact.

To provide solventless recovery of volatile organic compounds, therecovery system comprises a compartment that allows superheated vapor toflow in a continuous manner, i.e., as a stream. In one embodiment, thecompartment has a loop shape. In another embodiment, the compartmentcomprises a rotating drum. The compartment has an inlet through whichthe prepared biomass material can enter. In one embodiment, the inletcomprises a pressure tight rotary valve, plug screw, or other similardevice, which can assist in separating the prepared biomass material toincrease the surface area exposed to the superheated vapor stream.

In yet another embodiment, the system comprises a dewatering mechanismto remove at least a portion of the liquid in the prepared biomassmaterial before the liquid is vaporized. The liquid removal can occurbefore and/or while the prepared biomass material enters thecompartment. The liquid from the prepared biomass material contains atleast one volatile organic compound, which can be recovered by furtherprocessing the liquid, such as feeding the liquid to a distillationcolumn. The liquid can be routed directly to further processing unit,such as a distillation column. Alternatively or in addition to, thesystem further includes a collection unit to collect the liquid removedfrom the prepared biomass material. Any portion of the collected liquidcan then be further processed.

In one embodiment, the dewatering mechanism comprises a componentadapted to squeeze the liquid from the prepared biomass material. Insuch an embodiment, the squeezing can be performed while the preparedbiomass material is being fed into the compartment. For instance, theinlet can comprise a squeezing mechanism to squeeze liquid from theprepared biomass material as it is introduced into the compartment.Alternatively or in addition to, the squeezing can be performedseparately before the prepared biomass material enters the compartment.A non-limiting example of such a squeezing mechanism is a screw plugfeeder.

In one embodiment, the liquid removal mechanism comprises a mechanicalpress. Non-limiting examples of types of mechanical presses include beltfilter presses, V-type presses, ring presses, screw presses and drumpresses. In a particular embodiment of a belt filter press, the preparedbiomass material is sandwiched between two porous belts, which arepassed over and under rollers to squeeze moisture out. In anotherparticular embodiment, a drum press comprises a perforated drum with arevolving press roll inside it that presses material against theperforated drum. In yet another embodiment, in a bowl centrifuge, thematerial enters a conical, spinning bowl in which solids accumulate onthe perimeter.

The compartment provides a space where the superheated vapor stream cancontact the prepared biomass material to vaporize the liquid from theprepared biomass material. The vaporization of at least a portion of theliquid provides a gas component and a solid component of the preparedbiomass material. The system further comprises a separating unit wherethe solid component of the prepared biomass material can be separatedfrom the gas component, so each component can be removed as desired forfurther processing. In one embodiment, the separating unit comprises acentrifugal collector. An example of such centrifugal collector is highefficiency cyclone equipment. In a preferred embodiment, the separatingunit also serves as an outlet for the solid component. For example, theseparating unit can discharge the solid component from the solventlessrecovery system. There is a separate outlet for the gas component whereit can exit the system for further processing, such as distillation. Inone embodiment, the separating unit is further coupled to a secondpressure tight rotary valve or the like to extrude or discharge thesolid component. In one embodiment, the superheated vapor is maintainedat a target or desired temperature above its saturation temperature by aheat exchange component coupled to a heat source where the superheatedvapor does not contact the heat source. The heat transfer between theheat source and the system occurs via convection to the superheatedvapor. In one embodiment, the heat source can include electricalelements or hot vapors through an appropriate heat exchanger. In oneembodiment, the operating pressure is in a range from about 1 psig toabout 120 psig. In a preferred embodiment, the operating pressure is ina range from about 3 psig to about 40 psig. In a particularly preferredembodiment, the system is pressurized at an operating pressure of about60 psig to force the vapor component from the system.

In one embodiment, at start up of the recovery system, the preparedbiomass material is introduced into the compartment via the inlet. Steamis initially used as the superheated vapor to initially vaporize theliquid in the prepared biomass material. The superheated vaporcontinuously moves through the compartment. When the prepared biomassmaterial enters the superheated vapor stream, it becomes fluidized whereit flows through the compartment like a fluid. As the prepared biomassmaterial is introduced, it comes into contact with the superheated vaporstream. Heat from the superheated vapor is transferred to the preparedbiomass material and vaporizes at least a portion of the liquid in theprepared biomass material and is separated from the solid component,which may still contain moisture. The gas component contains volatileorganic compound(s) produced in the prepared biomass material. In apreferred embodiment, as liquid from the prepared biomass materialbegins to vaporize, at least a portion of the vaporized liquid can berecycled in the system as superheated fluid. That is, during any onecycle, at least a portion of the vaporized liquid remains in thecompartment to serve as superheated vapor instead of being collected forfurther processing, until the next cycle where more prepared biomassmaterial is fed into the system.

In a preferred embodiment, during the initial start up procedure, thesuperheated fluid can be purged as needed, preferably continuously(intermittently or constantly), until steady state is achieved where thesuperheated vapor comprises only vaporized liquid of the preparedbiomass material. The gas component and solid component can be collectedvia the respective outlet. Heat can be added continuously(intermittently or constantly) to the system via the heat exchangercoupled to the heat source to maintain the temperature of thesuperheated vapor, to maintain a desired operating pressure in thesystem, or to maintain a target vaporization rate. Various conditions ofthe system, such as flow rate of the superheated vapor stream, pressure,and temperature, can be adjusted to achieve the desired liquid and/orvolatile organic compounds removal rate.

In one embodiment, the collected gas component is condensed for furtherprocessing, such as being transferred to a purification process toobtain a higher concentration of the volatile organic compound(s) ofchoice. In a preferred embodiment, the collected gas component is feddirectly into a distillation column, which provides savings of energynot used to condense the gas component. In another embodiment, the gascomponent is condensed and fed to the next purification step as liquid.

In one embodiment, before entering the recovery phase, the preparedbiomass material has an initial liquid content of about at least 10 wt %and up to about 80 wt % based on the biomass material. In a particularembodiment, the initial liquid content is at least about 50 wt % basedon the biomass material. In one embodiment, the initial liquid contentcomprises from about 2 to 50 wt %, and preferably from about 4 to 10 wt% ethanol based on the initial liquid content.

In one embodiment, the solid component collected contains from about 5wt % to about 70 wt %, and preferably from about 30 wt % to about 50 wt%, liquid depending on the ethanol removal target. In another component,the collected gas component contains between about 1 wt % and about 50wt % ethanol, preferably between about 4 wt % and about 15 wt % ethanol.In one embodiment, the recovery system recovers from about 50% to about100% of the volatile organic compounds contained in the prepared biomassmaterial. The residence time of the prepared biomass varies based on anumber of factors, including the volatile organic compound removaltarget. In one embodiment, the residence time of the prepared biomassmaterial in the compartment is in a range of about 1 to about 10seconds. In one embodiment, the recovery system can be operated betweenabout 0.06 barg and about 16 barg. The term “barg” refers to bar gaugeas understood by one of ordinary skill in the art, and 1 bar equals to0.1 MegaPascal. In one embodiment, the gas in the recovery system has atemperature in a range of about 100° C. to about 375° C., particularlyfrom about 104° C. to about 372° C., and the solid component exiting thesystem has a temperature of less than about 50° C. The collected solidcomponent can be used in other applications. Non-limiting examplesinclude animal feed, feed for a biomass burner to supply process energyor generate electricity, or further converted to ethanol by means of acellulosic ethanol process (either re-ferment in a silage pile, or feedto a pre-treatment unit for any cellulosic ethanol process) or a feedfor any other bio-fuel process requiring ligno-cellulosic biomass.

The operating conditions of the solventless recovery system include atleast temperature, pressure, flow velocity, and residence time. Any oneor combination of these conditions can be controlled to achieve a targetor desired removal target, such as the amount of the initial liquidcontent removed or the amount of the liquid remaining in the separatedliquid component exiting the recovery system. In one embodiment, atleast one operating condition is controlled to achieve removal of about10-90 wt %, preferably about 45-65 wt %, and more preferably about 50 wt%, of the initial liquid content.

In a preferred embodiment, increasing the temperature of the system atconstant pressure will cause the liquid in the biomass to be vaporizedmore quickly and thus for a given residence time will cause a higherpercentage of the liquid in the biomass to be evaporated. The vapor flowrate exiting the system has to be controlled to match the rate ofvaporization of liquid from the biomass in order to achieve steady stateand can also be used as a mechanism to control the system pressure.Increasing the system pressure will cause more energy to be stored inthe vapor phase in the system which can then be used to aid in furtherprocessing or to help move the vapor to the next downstream processingunit. Increasing the biomass residence time in the system causes moreheat to be transferred from the vapor phase to the biomass resulting inmore liquid being vaporized.

In a specific exemplary embodiment, the recovery system comprises aclosed loop pneumatic superheated steam dryer, which can be obtainedfrom commercially available sources. In one embodiment, the closed looppneumatic superheated steam dryer is an SSD™ model of GEA Barr-RosinInc. Other suitable commercially available equipment include theSuperheated Steam Processor, SSP™ from GEA Barr-Rosin Inc, the RingDryer from several companies including GEA Ban-Rosin Inc. and Dupps; theAirless Dryer from Dupps; the QuadPass™ Rotary Drum Dryer fromDuppsEvactherm™, Vacuum Superheated Steam Drying from Eirich; the rotarydrum dryer using superheated vapor from Swiss Combi Ecodry; and theairless dryer from Ceramic Drying Systems Ltd.

Still other types of indirect dryers that could serve as the volatileorganics recovery unit for this process are batch tray dryers,indirect-contact rotary dryers, rotating batch vacuum dryers, andagitated dryers. The basic principle for these dryers is that they willbe enclosed and attached to a vacuum system to remove vapors from thesolids as they are generated (also by lowering the pressure with thevacuum the volatiles are removed more easily). The wet solids contact ahot surface such as trays or paddles, the heat is transferred to the wetsolids causing the liquids to evaporate so they can be collected in thevacuum system and condensed.

FIG. 1 illustrates an exemplary VOC recovery system and processemploying a superheated steam dryer, referenced as system 100. In aparticular embodiment, the superheated steam dry can be obtained fromGEA Barr-Rosin Inc. In FIG. 1, prepared biomass material 1 containingethanol and/or other VOCs following solid state fermentation in thesilage piles is fed into compartment 3 through input 2. In theparticular embodiment shown, input 2 comprises a screw extruder. Asshown in FIG. 1, at least a portion of the liquid of the preparedbiomass material 1 is removed prior to entering compartment 3. Thedewatering mechanism can be a screw plug feeder through which theprepared biomass material 1 passes. At least a portion of the liquidremoved from biomass material 1 can be routed directly to distillationstep 11 via stream 15 without going through recovery system 100.Optionally, a delumper can be coupled to the output of the dewateringmechanism can be used to facilitate introduction of the dewateredbiomass material into compartment 3.

Referring to FIG. 1, recovery system 100 comprises compartment 3, whichcan be pressurized, shown as a conduit that has an appropriate diameter,length and shape, adapted to provide the desired operating conditions,such as residence time of prepared biomass material 1, heat transfer tothe superheated vapor, and operating pressure and temperature. Afterentering compartment 3, during steady state operation, prepared biomassmaterial 1 contacts superheated vapor flowing through system 100 at adesired temperature and becomes fluidized. As described above, in apreferred embodiment, the superheated vapor, or at least a portionthereof, is vapor component obtained from prepared biomass materialspreviously fed into system 100 for VOC recovery. The fluidized biomassflows through compartment 3 at a target flow rate and remains in contactwith the superheated vapor for a target residence time sufficient toevaporate the desired amount of liquid from prepared biomass material 1.In the embodiment shown, the flow of the superheated vapor and preparedbiomass material 1 through system 100 is facilitated by system fan 14.System 100 can have one or more fans. The flow rate or velocity of thesuperheated vapor and biomass material 1 can be controlled by system fan14. Biomass material 1 flows through compartment 3 and reachesseparating unit 4, which is preferably a cyclone separator, where avapor component and a solid component of biomass material 1 areseparated from each other. As shown, the vapor component is routed awayfrom the solid component via overhead stream 5 and the remaining portionof biomass material 1 is considered a solid component, which isdischarged from separating unit 4 as solid component 7, preferably byscrew extruder 6. At least a portion of the discharged solid component 7can be used as animal feed, burner fuel, or biomass feedstock for otherbio-fuels processes.

Referring to FIG. 1, a portion of the vapor component, referenced asstream 8, is retained and recycled as a portion of the superheated vaporused to vaporize newly introduced prepared biomass material. In theembodiment shown, the retained vapor component in stream 8 is routedthrough heat exchanger 9 to heat it to the target operating temperature.The heat source can include steam, electricity, hot flue gases or anyother applicable heating source known to those skilled in the art.

In a preferred embodiment, the temperature is controlled such that thepressure in the system is maintained at the target and there is adequateenergy present to evaporate the desired amount of liquid. The pressurecan also be controlled by the flow rate of the superheated vapor streamand the heat input to heat exchanger 9. Preferably, recovery system 100operates continuously where prepared biomass material 1 is continuouslyfed at a desired rate, and vapor component 10 and solid component 6 arecontinuously removed at a continuous rate. In a preferred embodiment,“fresh” vapor component 8 from one run is retained continuously at atarget rate to be used as the superheated vapor stream for the next run.Any of these rates are adjustable to achieve the desired operatingconditions. As mentioned, system fan 14 circulates the superheated vaporstream through system 100 and can be adjusted to obtain the target flowrate or velocity.

Referring to FIG. 1, the remaining portion of vapor component stream 5,represented as numeral 10 is routed to a distillation step 11. Dependingon the distillation configuration, vapor component portion 10 may becondensed before further purification or preferably fed directly intothe distillation column as a vapor. In a preferred embodiment, thedistillation product from distillation step 11 has an ethanol content ofabout 95.6 wt % ethanol (the ethanol/water azeotrope), which can furtherbe purified to above about 99 wt % using common ethanol dehydrationtechnology, which is shown as step 12. The final ethanol product 13 willthen typically be used as a biofuel for blending with gasoline.

FIG. 2 illustrates another exemplary recovery system and processemploying a superheated steam dryer, referenced as system 200 that isrepresentative of the Ring Dryer provided by various manufacturers.Prepared biomass material 201 is fed into system 200 through input 202,which preferably comprises a screw extruder. In one embodiment, least aportion of the liquid of the prepared biomass material 201 is removedprior to entering system 200. The dewatering mechanism can be a screwplug feeder through which the prepared biomass material 201 passes. Atleast a portion of the liquid removed from biomass material 201 can berouted directly to distillation step 211 via stream 215 without goingthrough recovery system 200. Optionally, a delumper can be coupled tothe output of the dewatering mechanism can be used to facilitateintroduction of the dewatered biomass material into compartment 203.

Referring to FIG. 2, recovery system 200 comprises compartment 203,which preferably comprises a rotating drum that provides the targetoperating conditions for VOC recovery, including residence time ofprepared biomass material 201, heat transfer to the superheated vapor,and operating pressure and temperature. After entering compartment 203,during steady state operation, prepared biomass material 201 contactssuperheated vapor flowing through system 200 at the operatingtemperature and flow rate and becomes fluidized. As described above, ina preferred embodiment, the superheated vapor, or at least a portionthereof, is the vapor component obtained from prepared biomass materialpreviously fed into system 200 for VOC recovery. The fluidized biomassflows through compartment 203 at a target flow rate and remains incontact with the superheated vapor for the target residence time toachieve the target vaporization of liquid from the biomass. Thefluidized biomass then reaches separating unit 204, which is preferablya cyclone separator, where the vapor component and solid component areseparated from each other. As shown, the vapor component is routed awayfrom the solid component through overhead stream 205, and solidcomponent 207 is discharged from separating unit 204. As shown, solidcomponent 207 exits system 100 via extruder 206 and can have subsequentuses as mentioned above. A portion of the vapor component, referenced asstream 208, is retained and recycled as a portion of the superheatedvapor used to vaporize newly introduced prepared biomass material. Asshown, retained vapor component 208 is routed through heat exchanger 209to heat it to the desired temperature. The heat source or thermal energysource can include steam, electricity, hot flue gases or any otherdesired heating source. As shown, hot flue gas is used. The temperatureis controlled such that the pressure in the system is maintained at thetarget and there is adequate energy present to evaporate the desiredamount of liquid. The pressure can also be controlled by the flow rateof the superheated vapor stream and the heat input to heat exchanger209.

Referring to FIG. 2, the remaining portion of vapor component stream205, represented as numeral 210 is routed to a distillation step.Depending on the distillation configuration, vapor component portion 210may be condensed before further purification or preferably fed directlyinto the distillation column as a vapor. The product from thedistillation step can further be concentrated using known processes.

Preferably, recovery system 200 operates continuously where preparedbiomass material 201 is continuously fed at a desired rate, and vaporcomponent 210 and solid component 206 are continuously removed at acontinuous rate. In a preferred embodiment, “fresh” vapor component 208from one run is retained continuously at a target rate to be used as thesuperheated vapor stream for the next run. All these rates areadjustable to achieve the desired operating conditions. System fan 214creates a circulating loop of superheated vapor stream and can beadjusted to obtain the target flow rate.

By using a solventless recovery system according to aspects of thepresent invention, the points of heat transfer in the system, i.e.,addition of heat to the system and heat transfer to the prepared biomassmaterial, take place in the vapor phase in a preferred embodiment, whichprovides an advantage cause vapor phase heat transfer (convection) ismore efficient than solid phase heat transfer (conduction) in theprepared biomass material, which is a bad conductor because it hasinsulating properties. As mentioned above, in certain embodiments, oncesteady state is reached no vapor other than that vaporized from theliquid of the prepared biomass material contacts the solid component andgas component of the prepared biomass material in the system, whichprevents or reduces dilution that would come from the addition ofprocess steam or other vapor to replenish the superheated vapor stream.The collected gas component can be fed directly to a distillation columnfor separation of the desired volatile organic compound(s), which canprovide significant energy savings. The advantage of this system is thatthe vapors that contact the wet solids are only those vapors that havebeen previously removed from the solids so that there is no dilution orexplosion risk, etc.

The following examples are presented to further illustrate theinvention, but they are not to be construed as limiting the scope of theinvention.

ILLUSTRATIVE EMBODIMENTS Example A

In this example, various samples of fresh chopped sorghum are mixed witha variety of added components as listed in Table A.1 and are stored insilage tubes for 258 days. The amount of ethanol produced in eachexperiment is shown in the bottom row of the table. The addition ratesof the selected additives are shown in Table A.2.

TABLE A.1 2010 Experiments WITHOUT WITHOUT WITHOUT WITHOUT WITHOUT WITHWITH WITH WITH ACID ACID ACID ACID ACID ACID ACID ACID ACID Experiment #1 2 3 4 5 6 7 8 9 Estimated Mass 20 tonnes 20 tonnes 20 tonnes 20 tonnes20 tonnes 20 tonnes 20 tonnes 20 tonnes 20 tonnes Moisture 68% 68% 68%68% 68% 68% 68% 68% 68% Content Storage Method Silage Silage SilageSilage Silage Silage Silage Silage Silage Tube Tube Tube Tube Tube TubeTube Tube Tube Primary Yeast Ethanol Ethanol Ethanol Ethanol EthanolEthanol Ethanol Ethanol Ethanol Red Red Red Red Red Red Red Red RedHelper Yeast BioSaf BioSaf BioSaf BioSaf BioSaf Bacterial LactrolLactrol Lactrol Lactrol Lactrol Lactrol Lactrol Lactrol LactrolInhibitor Cellulose to Cellulase Cellulase Cellulase Cellulase CellulaseCellulase Glucose CE-2 CE-2 CE-2 CE-2 CE-2 CE-2 Starch to AmylaseAmylase Amylase Amylase Amylase Amylase Glucose Other enzyme LiquicellLiquicell activities: 2500 2500 accessory enzymes Result (gallons 36 4835 35 46 36 45 36 42 Ethanol/initial dry metric tonne)

TABLE A.2 ADDITIVE Rates LACTROL  1.6 g/wet tonne Ethanol Red 0.11kg/wet tonne BioSaf 0.11 kg/wet tonne Cellulase CE-2 0.22 kg/wet tonneAmylase 0.11 kg/wet tonne Liquicell 0.11 kg/wet tonne 93% ConcentratedSulfuric Acid 0.42 L/wet tonne

The experiments of Example A demonstrated the principle of ethanolproduction in silage piles and the duration of that storage. Further,they demonstrated effects of certain additive. All cases in the exampleproduced a significant amount of ethanol indicating that embodiments ofthe invention can be quite robust. In Table A.1, all but the last rowdescribe what additives went into the test. The bottom row describes theresult in terms of ethanol production in that experiment. In general,the experiments with acid showed superior stability to those withoutacid. Nevertheless, experiments without acid still yielded ethanolproduction, indicating that an acid additive is optional.

Example B

In Example B, three additional experiments are shown in Table B.1. Theaddition rates of the selected additives are shown in Table B.2.

TABLE B.1 2011 Experiments WITH ACID WITH ACID WITH ACID Experiment # 12 3 Estimated Mass 450 tonnes 450 tonnes 100 tonnes Moisture Content 76%76% 69% Storage Method Bunker Bunker Silage Tube Yeast LallemandLallemand Lallemand Liquid Liquid Liquid Yeast Yeast Yeast BacterialInhibitor Lactrol Lactrol Lactrol Cellulose to Glucose NovozymesNovozymes Novozymes Cellic Cellic Cellic CTec2 CTec2 CTec2 Chop Size 3mm 13 mm 13 mm Result (gallons  50  51  48 Ethanol/initial dry ton) Daysin Storage 330 330 315

TABLE B.2 ADDITIVE Rates LACTROL 3.2 g/wet ton Lallemand StabilizedLiquid 18 fl oz/wet ton Yeast Novozymes Celtic CTec2 20 fl oz/wet ton9.3% Concentrated Sulfuric 3.8 L/wet ton Acid

The experiments of Example B also demonstrated the effects of certainadditives, as well as the effects of scale. Experiments 1 and 2 ofExample B were conducted in the same bunker demonstrating that thisfermentation technology is stable and efficient at commercial scale.

Example C

In these experiments, the GEA SSD™ is used as the solventless recoveryunit. In Table C.1 below, the top section describes certain propertiesof the prepared biomass material that were fed to the system. The nextsection describes the condition of the solid component exiting thesolvent less recovery system. The third section shows the operatingconditions of the solvent less recovery system and the last sectiongives the recovery rates of the main liquid components: ethanol, aceticacid and water. What is shown here in all cases is the ability torecover >90% of the ethanol that is in the solids (100% in some cases),and the ability to vary the amount of ethanol and water recovery basedon the conditions of the solvent less recovery system. Samples 10, 11,and 12 below also contain significant amounts of acetic acid, and showthat this process can also be used for the efficient recovery of aceticacid

TABLE C.1 Sample Sample Sample Sample Sample Sample Sample Sample SampleSample Sample Sample 1 2 3 4 5 6 7 8 9 10 11 12 Prepared BiomassComposition (“Feed”) Liquid in Feed 80.2% 79.9%   82% 79% 31% 82% 80%80% 58% 70% 70% 70% (%) Water in Liquid — 95.1%   94.9%   95.0%  99.9%   95.7%   95.8%   95.8%   98.6%   94.6%   0.946 0.946 (%) Ethanolin — 4.2%  4.4%  4.5%  0.0%  3.9%  3.8%  3.8%  0.6%  2.8%  0.028 0.028Liquid (%) Acetic Acid in — 0.7%  0.7%  0.5%  0.1%  0.4%  0.4%  0.4% 0.8%  2.6%  2.6%  2.6%  Liquid (%) Solid Component Liquid in Solid 66.4%58% 39% 31%  7% 67% 49% 38% 37% 55% 46% 39% Component (%) SolidComponent 83 87 89 90 89 86 73 87 82 88 82 91 Temperature (F.) OperatingConditions Vapor 349 423 594 428 487 471 426 446 311 297 401 441Temperature at Inlet (F.) Exhaust 225 235 295 370 401 275 298 347 307237 302 351 Temperature (F.) Operating 3 3 3 40 20 3 2 20 20 3 3 20Pressure (psig) % Removal Ethanol — 95% 99% 100%  100%  96% 95% 99%100%  90% 93% 98% Acetic Acid — 45% 94% 98% 100%  69% 24% 96% 100%  82%84% 96% Water — 64% 86% 92% 90% 61% 76% 84% 72% 46% 64% 76% TotalLiquids — 65% 87% 92% 90% 63% 77% 85% 72% 48% 66% 77%

Example D

Some of the conditions tested provided sufficient pre-treatment of thebiomass coming out of the volatiles recovery unit to allow forconversion of some of the remaining cellulose to biomass. Conditionsfrom Samples 6 and 7 in Example C above produced statisticallysignificant quantities of ethanol when a small amount of enzymes andyeast were added to the sample of the remaining solid component and werestored in an anaerobic environment. Other conditions tested were fromSample 3, 4, 8, 10, and 12. These samples produced no ethanol whenplaced in the same test conditions as samples 6 and 7. The conclusionfrom this is that under the test conditions described in sample numbers6 and 7, certain embodiments of the present invention can be used forthe subsequent production of cellulosic ethanol by ensiling the solidcomponent from the volatile organics recovery unit.

Example E

In these experiments, a 700 ton pile was prepared according to aspectsof the invention and stored in a bunker. On day 504 of storage in thebunker, three samples were taken from the top, center, and bottom ofpile, all showed similar levels of compounds. The samples were stored at4 degrees C.

Sample Prep:

The samples were squeezed through a 60 mL syringe without filtration,and the liquid was collected.

Testing Conditions:

1) The samples were tested with an Agilent 7890 GC with a 5975 C massspectrometer under the following conditions:

-   -   Agilent CTC autosampler with headspace option    -   2.5 ml heated syringe, 1 ml injection size into S/SL inlet @ 130        C, 20:1 split ratio    -   Separation on a 60M DB 624 column, 0.25 id with 1.4 μm film        The samples were prepared by place 0.25 ml into a 20 ml        headspace vial. 1 ml of vapor was injected after equilibration        at 60 C for 10 min.        2) The samples were tested with an Agilent 6890 GC with a 5973        Mass Spectrometer under the following conditions:    -   Perkin Elmer Turbomatrix 40 headspace autosampler    -   60 M DB5 MS 0.25 mm id, 1.0 μm film 100:1 split ratio        The samples were prepared by place 0.25 ml into a 20 ml        headspace vial. Vapor was injected for 20 seconds after        equilibration at 90 C for 15 min.

The following compounds were identified in the headspace under bothconditions, indicating that these compounds were produced and can bepotentially recovered using the solventless recovery system and capturedduring a subsequent distillation process in certain embodiments.

Acetaldehyde Methanol Ethanol Propanol Acetone Methyl acetate AcetoneEthyl formate n-propyl alcohol ethyl acetate 2-butanol 2-methyl-1-propanol 2-propen-1-ol Acetic acid 3-methyl-1-butanol 2-methyl-1-butanol 3-buten-2-ol

Further modifications and alternative embodiments of various aspects ofthe invention will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the invention. It is to beunderstood that the forms of the invention shown and described hereinare to be taken as the presently preferred embodiments. Elements andmaterials may be substituted for those illustrated and described herein,parts and processes may be reversed, and certain features of theinvention may be utilized independently, all as would be apparent to oneskilled in the art after having the benefit of this description of theinvention. Changes may be made in the elements described herein withoutdeparting from the spirit and scope of the invention as described in thefollowing claims.

We claim:
 1. A method for producing at least one volatile organiccompound comprising: generating at least about 10 tons of preparedbiomass material comprising at least one additive added to a solidbiomass comprising a sugar, wherein said at least one additive comprisea microbe, and optionally, an acid and/or an enzyme; storing theprepared biomass material for at least about 24 hours in a storagefacility to allow for the production of at least one volatile organiccompound from at least a portion of the sugar; and capturing the atleast one volatile organic compound by feeding the stored biomassmaterial to a solventless recovery system to separate the stored biomassmaterial into at least a gas component comprising the at least onevolatile organic compound and a solid component.
 2. The method of claim1 wherein at least about 700 tons of prepared biomass material isgenerated in a time period in a range of about 1 to 7 months.
 3. Themethod of claim 2, wherein at least about 25,000 tons of preparedbiomass material is generated.
 4. The method of claim 3, wherein atleast about 100,000 tons of prepared biomass material is generated. 5.The method of claim 4, wherein at least about 1,200,000 tons of preparedbiomass is generated.
 6. The method of claim 1, wherein about 14-16gallons of ethanol is recovered per one ton of prepared biomassmaterial.
 7. The method of claim 1 wherein the biomass substancecomprises at least one fermentable sugar producing plant.
 8. The methodof claim 7 wherein the at least one fermentable sugar producing plantcomprises at least one of sorghum, sugarcane, sugar beet, energy cane,and any combination thereof.
 9. The method of claim 7 wherein theprepared biomass material comprises at least two different plant types,wherein each plant type has different harvest seasons.
 10. The method ofclaim 7 wherein the at least one sugar-producing plant is harvested whensaid plant has reached at least about 80% of its sugar productionpotential.
 11. The method of claim 1, wherein the solid biomasscomprises a stalk component and a leaf component of the at least onesugar-producing plant.
 14. The method of claim 1 wherein the storingstep comprises storing the prepared biomass material for a time periodin a range of about 72 hours to about 700 days.
 16. The method of claim1 wherein the storing step comprises storing the prepared biomassmaterial for a time period sufficient to allow a conversion efficiencyof sugar to at least one volatile organic compound of at least about95%.
 19. The method of claim 1 wherein the storage facility is locatedabout 0.5 mile from the solventless recovery system.
 21. The method ofclaim 1 wherein the storing step further comprises forming at least onepile of prepared biomass material having a height of at least about 10feet.
 23. The method of claim 1 wherein the forming of the at least onepile further comprises compacting at least a portion of the preparedbiomass material to facilitate establishing of an anaerobic environment.24. The method of claim 1 wherein the capturing step comprises:introducing the prepared biomass material to an enclosed compartment ofa solventless recovery system, wherein the prepared biomass materialcontains one or more volatile organic compounds; contacting the preparedbiomass material with a superheated vapor stream in the enclosedcompartment to vaporize at least a portion of an initial liquid contentin the prepared biomass material, said superheated vapor streamcomprising at least one volatile organic compound; separating a gascomponent and a solid component from the prepared biomass material, saidgas component comprising at least one volatile organic compound; andretaining at least a portion of the gas component for use as part of thesuperheated vapor stream.
 25. A method for producing a storable wetbiomass containing volatile organic compounds, said method comprising:adding at least one additive to at least about 10 tons of a solidbiomass to generate a prepared biomass material, said solid biomasscomprising a sugar-producing plant, wherein said at least one additivecomprises a microbe, and optionally, an acid and/or an enzyme; andallowing conversion of at least a portion of the sugar in the preparedbiomass material into a volatile organic compound; wherein the biomassmaterial is capable of being stored for about 700 days withoutsignificant degradation of the volatile organic compound.
 27. The methodof claim 26 further comprising: introducing the prepared biomassmaterial to an enclosed compartment of a solventless recovery system,wherein the prepared biomass material contains one or more volatileorganic compounds; contacting the prepared biomass material with asuperheated vapor stream in the enclosed compartment to vaporize atleast a portion of an initial liquid content in the prepared biomassmaterial, said superheated vapor stream comprising at least one volatileorganic compound; separating a gas component and a solid component fromthe prepared biomass material, said gas component comprising at leastone volatile organic compound; and retaining at least a portion of thegas component for use as part of the superheated vapor stream.